You DEFINITELY need a stand mixer, preferably one with a dough hook attachment, to make this fondant. I had no problems making or using the fondant, though. It worked just as well as promised! It was actually a little more pliable than regular fondant, which helped prevent cracks.
I carved the cars out of rice krispie treats (you just compress the mixture to make it really dense for carving) because cake can be really heavy. I knew that I was going to place the cars on two round cakes (a figure eight "racetrack") and didn't want them to sink or be unstable.
There are several things I would add if I had more time. I should have taken the extra few minutes to add racing stripes, like I had planned. I would definitely have preferred to have more details on the cars, but overall I think they look pretty good for my first try at fondant-covered rice krispie treats.
I would have liked to have made the cake base bigger, too, but have such limited space to work in. These were already 16" rounds. I also needed to make sure that it fit in the car for delivery!
Overall, I'm not completely happy with it but I certainly learned a lot!